When you realize you have a flat tire, it's important to find a safe location to change it. Move your car to a level, flat surface away from traffic, turn on your hazard lights, and engage the parking brake.
Find a safe location
Use a jack to lift the car off the ground and remove the lug nuts with a lug wrench. Then, remove the flat tire and replace it with the spare tire. Tighten the lug nuts by hand as much as possible.
Remove the flat tire
Use the jack to lower the car back to the ground and remove the jack. Use the lug wrench to fully tighten the lug nuts in a star pattern to ensure even tightening. Finally, check the tire pressure of the spare tire and get the flat tire repaired or replaced as soon as possible.